Santangelo, who will enter his sixth season with MASN, is the fifth TV partner for Carpenter, who has worked with Tom Paciorek, Don Sutton, Rob Dibble and Knight.
"Excited and honored to begin my 16th year in this franchise," Santangelo said on Twitter. "Thank you to the Nats and MASN for making that possible."
Kolko is entering his third year with the Nationals. He is also a contributor on the MLB Network.
"Yup, I will indeed be back as the on-field reporter for Nats broadcasts on MASN next season. Very excited," Kolko said on Twitter.
Holliday, who is known for his play-by-play with Maryland football and basketball, has been the studio host since the Nationals' inaugural season in 2005. He sometimes fills in for Carpenter.
Knight, who is best known for being a World Series MVP with the Mets in 1986, has been a studio analyst since 2007. He also fills in for Santangelo on occasion.
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All theTime. He also can be found on Twitter @WashingNats This story was not subject to the approval of Major League Baseball or its clubs.